Effect of preoperative oral nutritional supplements on clinical outcomes in patients undergoing surgery for gastrointestinal cancer: A systematic review and meta-analysis.

Background: The clinical benefit of preoperative oral nutritional supplements (ONS) in patients undergoing surgery for gastrointestinal cancer remains controversial.

Objective: To evaluate the effect of preoperative ONS on postoperative clinical outcomes in patients with gastrointestinal cancer.

Methods: We searched PubMed, EMBASE, Web of Science, Cochrane Library, Scopus, and the Chinese National Knowledge Infrastructure databases for randomized controlled trials evaluating preoperative ONS in patients undergoing surgery for gastrointestinal cancer from inception until April 2024. Two researchers independently assessed the quality of the included literature and performed statistical analyses using Review Manager 5.4 software.

Results: A total of 12 eligible studies with 1201 patients (600 ONS group and 601 control group) were included in this meta-analysis. Compared with a normal diet, preoperative ONS effectively reduced infectious complications (odds ratio = 0.63; 95% confidence interval [CI], 0.40-0.98; P = .04), white blood cell count (mean difference [MD] = -0.66; 95% CI, -1.04 to -0.28; P = .0007), C-reactive protein (MD = -0.26; 95% CI, -0.33 to -0.19; P < .00001), and markedly improved albumin levels (MD = 1.71; 95% CI, 0.97-2.46; P < .00001), prealbumin (MD = 24.80; 95% CI, 1.72-47.88; P = .04), immunoglobulin G (MD = 0.86; 95% CI, 0.44-1.28; P < .00001), CD4 T lymphocyte cells (MD = 3.06; 95% CI, 2.21-3.92; P < .00001), and CD4 T lymphocyte cells/CD8 T lymphocyte cells (MD = 0.33; 95% CI, 0.10-0.56; P = .004). However, there were no significant differences between the 2 groups in terms of noninfectious complications (odds ratio = 0.77; 95% CI, 0.39-1.53; P = .46), immunoglobulin A (MD = -0.21; 95% CI, -0.44 to 0.02; P = .08) or length of hospital stay (MD = -0.04; 95% CI, -0.71 to 0.64; P = .92).

Conclusion: Preoperative ONS may effectively reduce postoperative infectious complications, improve postoperative nutritional status and immune function, and relieve the inflammatory response in gastrointestinal cancer patients. Therefore, we recommend that preoperative nutrition could be optimized with ONS in patients undergoing gastrointestinal cancer surgery.